1. Technical Field
The present invention relates to a gate driver used for a power IC, and the like, and more particularly, to a gate driver capable of improving a driving speed of a gate driver without increasing current of a current source.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a structure of a gate driver according to the related art.
Referring to FIG. 1, the gate driver according to the related art is configured to include a first power switch 110, a second power switch 120, an inverter unit 130, a level shifter 140, and an amplification unit 150. The first power switch 110 is a power transistor PMOS for sourcing current and the second power switch 120 is a power transistor NMOS for sinking current.
The inverter unit 130 is to efficiently drive the second power switch 120 and the first power switch 110. In this case, current drivability of each inverter INV2 to INV9 of the inverter unit 130 may be represented by a size as follows.
INV2<INV3<NV4<INV5, INV6<INV7<INV8<INV9
Meanwhile, when withstand voltage of gates of the first power switch 110 and the second power switch 120 are smaller than power voltage VDD3, gate driving voltage is limited, such that a maximum swing of the gate voltage of the first power switch 110 is limited between VDD2 and 0V and a maximum swing of the gate voltage of the second power switch 120 is limited between VDD1 and 0V. Therefore, auxiliary power supplies VDD1 and VDD2 are required and in this configuration, a level shifter 140 configured of transistors M1 and M2 is required to drive the first power switch 110.
When input current IN from the outside is high, the M1 of the level shifter 140 is turned on and current of a current source CS connected with the level shifter 140 flows through the M1. The current is copied to a transistor M8 of an amplification unit 150, while the current the M2 is 0 and thus current of a M6 is 0. Therefore, an output from the M8 and the M6 becomes a low level. When the input current IN is low, the current of the M8 is 0, and therefore the output from the M8 and the M6 becomes a high level.
In order to rapidly turn on/off the first power switch MP, an operation of the level shifter 140 and the amplification unit 150 needs to be fasts. A speed of the amplification unit 150 is in proportion to a current quantity of the current source CS that is connected with the level shifter 140. Therefore, when the current of the current source CS is increased, a speed of the gate driver may be improved. As described above, however, there is a problem in that current is increased, and thus power consumption is increased.